RAM

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single vs multi channel:

single: all banks of RAM share a single 64 bit bus to the CPU

multi: the banks may be grouped together to form a wider bus 128 or 192

multi must be installed in matched sets

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expansion slots:

sound, graphics, network, serial or parallel cards, usb, storage, modem, wireless, tv tuner for cable television connection, video capture card, riser card (for tight space cases needing more expansion options)

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Storage devices:

traditional internal hard disk drives: the spinning platter type of hard disk

PATA = parallel AT attachment interface

SATA = serial AT attachment interface

non traditional

SSD = solid state drive

SCSI = small computer system interface

RAID = redundant array of inexpensive disks

external storage devices

USB = universal serial bus

firewire

eSATA

ETHERNET storage

NAS = network attached storage

SAN = storage attached network

cloud

SCSI: popular in enterprise because devices could be chained together. when chained, the last device needed to be terminated to stop signal bounce

most devices were hot swappable, meaning the device didn't need to be shut down in order for a defective device to be replaced

main types of SCSI:

narrow = 8 total components (1 controller, 7 devices)

wide = 16 total components (1 controller, 15 devices)

RAID:

takes multiple disks or storage volumes and combines them together

RAID 0:

requires minimum of two volumes. data is striped between the drives (write a block of data to one volume, write the next block to the other)

offers best performance out of all raid types (in most situations)

it is not fault tolerant, if one drive fails, the whole set is ruined

RAID ! (mirror set)

requires at least two volumes. data is mirrored between volumes ( the system writes each block of data at least twice)

offers extremely fast read times, but it is slow to write

fault tolerant. if one drive fails, data is still safe

RAID 5

requires a minimum of 3 volumes. stripes data between two drives and requires a parity block to the third drive in a rotating manner.

the parity block adds fault tolerance to the RAID. if any one disk fails, the data on it can be rebuilt by combining the data on the other two disks with the parity blocks.

not as fast as raid 0, but offers better performance than RAID 1 while still providing fault tolerance.

RAID 10:

requires a minimum of 4 volumes. a mirror set is also striped.

next to RAID 0, offers best performance while offering high degree of fault tolerance.